doc: Fix example with __next__() in PL/Python function

Per PEP 3114, iterator.next() has been renamed to iterator.__next__(),
and one example in the documentation still used next().  This caused the
example provided to fail the function creation since Python 2 is not
supported anymore since 19252e8ec93.

Author: Erik Wienhold
Discussion: https://postgr.es/m/173209043143.2092749.13692266486972491694@wrigleys.postgresql.org
Backpatch-through: 15

diff --git a/doc/src/sgml/plpython.sgml b/doc/src/sgml/plpython.sgml
index e5d51d6e9f5a4a4119e1c90e40d5173b10948cd8..bee817ea822a29e30a83415ee87addb03ecbb9e4 100644 (file)
--- a/doc/src/sgml/plpython.sgml
+++ b/doc/src/sgml/plpython.sgml
@@ -553,7 +553,7 @@ $$ LANGUAGE plpython3u;
 
     
      Iterator (any object providing __iter__ and
-      next methods)
+      __next__ methods)
      
       
 
@@ -569,7 +569,7 @@ AS $$
     def __iter__ (self):
       return self
 
-    def next (self):
+    def __next__(self):
       self.ndx += 1
       if self.ndx == len(self.who):
         raise StopIteration